FKBP5 and nonpapillary renal cell carcinoma: In addition, FKBP51 expression was more abundant in four RCC cell lines, ccRCC cell lines 786-O and Caki-1 and papillary RCC cell lines ACHN and Caki-2, than in the human kidney proximal tubular cell line (HK-2) (Fig. 1h).